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Keshty, Yassein

University of British Columbia

The Magnitude Scaling Factor (MSF) accounts for the number of loading cycles (Neq) from different magnitude earthquakes in the simplified liquefaction triggering procedures. Researchers developed existing MSF models for earthquakes with magnitudes up to Mw=8.0, typical of crustal sources, but have not rigorously studied model effectiveness for intra- and inter-plate subduction zone earthquakes. Utilizing the NGA-West2 and NGA-subduction ground motion databases, this study is a critical assessment of existing magnitude versus number of uniform equivalent cycles (Mw-Neq) relationships for use with subduction zone earthquakes. Findings indicate that existing relationships overestimate the number of cycles for inter-plate subduction events in the moderate to high magnitude range, and intra-plate earthquakes experience more loading cycles than predicted by these relationships. An improved regression model for Neq is introduced by addressing sources of variability, including regional differences and earthquake source type dependencies. This model incorporates normalized ground motion intensity measures—Cumulative Absolute Velocity (CAV) and Peak Ground Velocity (PGV), each scaled by the Peak Ground Acceleration (PGA)—to improve accuracy and provide a source-type and region-agnostic framework for liquefaction triggering assessments. The new Neq model serves as the grounds for the development of the Ground Motion Factor (GMF), which replaces the traditional MSF by eliminating dependence on solely Mw. A conditional CAV model is presented for use within the GMF framework; that incorporates active crustal and subduction subcrustal earthquake sources and uses PGA and Mw to condition CAV predictions. The new GMF and its associated Neq model are compatible with the current triggering framework, and its adoption is recommended for complex earthquake source types.

Text

2025-06-30

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/88606

Civil Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/